The pro-Democratic group Senate Majority PAC is going on air in Michigan and Arkansas today, part of its five-state, $3 million buy to push back on the major ad spending by the conservative Americans for Prosperity.

While they don’t mention the Koch brothers by name, both ads suggest Arkansas GOP Rep. Tom Cotton and former Michigan GOP Secretary of State Terri Lynn Land are beholden to the corporate and out-of-state interests that are spending money on their behalf.

The Arkansas ad focuses on Cotton’s time working for consulting firm McKinsey & Co. Democratic Sen. Mark Pryor is seen as one of the most vulnerable incumbents this cycle.

“Corporate special interests are spending millions to smear Mark Pryor and elect Tom Cotton. Before Congress, Cotton got paid handsomely working for insurance companies an corporate interests,” the ad says. “Now Cotton wants to end Medicare’s guarantee, giving billions in profits to insurance companies while costing seniors $6,000 more a year.”

Cotton’s campaign has pushed back, noting that while the candidate did work for McKinsey, he didn’t work directly with any insurance companies — a fact that Cotton’s former team leader at McKinsey confirmed to the Daily Caller this week.

A new Web ad from Pryor’s campaign Friday also hit Cotton, but on the issue of equal pay; in the ad, the female narrator says Cotton’s position on equal pay is “so … yesterday.”

In Michigan, where Democratic Rep. Gary Peters is in a margin-of-error contest with Land, the new ad says Land will side with insurance companies over Michigan voters.

“You already know that billionaires are paying for Terri Lynn Land’s Senate race,” the Michigan ad says. “What they already know is with Land, insurance companies will be able to deny you coverage when you get sick. Women’s access to preventive healthcare would be cut while their costs would increase.”

Land spokeswoman Heather Swift called the SMP ad “yet another lie.”

“Michiganders support Terri because they know she stands for real healthcare reform that puts the power back into the hands of Michigan’s women, families and doctors—not in the hands of Washington bureaucrats,” she said in a statement.

These ads come on the heels of record spending by AFP in key races across the country. The conservative group has already spent millions attacking Peters and Pryor on Obamacare.

Senate Majority PAC has worked to combat AFP in many of these races, though in most cases, their spending is still dwarfed by AFP’s ad buys. SMP has also run ads in Louisiana, Colorado, Iowa, North Carolina, Massachusetts, New Hampshire, Kentucky and Alaska this cycle.